1. Field of the Invention
The present invention relates to an office machine keyboard comprising a layer of elastic material shaped with individually depressible reliefs constituting the keys of the keyboard.
2. Description of the Prior Art
Keyboards of elastic material solve the problems regarding, for example, infiltration of foreign bodies into the interior of keyboard itself, insulation of the fingering surface or area from any internal electrical apparatus there may be, and absorption of the noise typical of office machines.
These keyboards are generally mounted on a rigid supporting surface provided with holes allowing the passage of rigid shanks or stems which connect each key with the encoding device located on the said supporting surface.
A very important problem arising in keyboards of elastic material is the production of the characters corresponding to the keys.
One known solution to this problem provides for the formation of cavities or recesses having the form of the characters in the fingering surfaces of the keys of elastic material; by filling the said cavities with material of a different colour, the characters themselves show up clearly.
This solution and other similar solutions are very complex and, moreover, good adhesion of the two elastic materials in the course of time is not certain, so that the character tends to become damaged, with negative aesthetic results.
Another known solution provides for the use of inserts on which the character is printed. These inserts are cemented to the bottom surface of a layer of transparent elastic material the top surface of which acts as the fingering surface.
This solution and other similar solutions have disadvantages connected with the complexity of the process of construction and with the problem of adhesion between the insert and the elastic material.